1. Field of the Invention
The present invention relates to a radiation image pickup apparatus for capturing a radiation image of a subject.
2. Description of the Related Art
There is known a system for recording radiation image information of a subject such as a human body with a stimulable phosphor, and reproducing the recorded radiation image information on a photosensitive medium such as a photographic film, or displaying the recorded radiation image information on a display device such as a CRT or the like.
When a radiation energy such as X-rays, xcex1-rays, xcex3-rays, electron beams, ultraviolet radiation, or the like is applied to a certain phosphor, it stores part of the applied radiation energy. When stimulating light such as visible light is subsequently applied to the phosphor, the phosphor emits light depending the stored radiation energy. Such a phosphor is referred to as a stimulable phosphor. A stimulable phosphor is usually used in the form of a sheet which is referred to as a stimulable phosphor sheet, for the ease with which it can be handled.
The above known system comprises a built-in radiation image information reading apparatus which includes a recording section for temporarily recording radiation image information of a subject on a stimulable phosphor sheet, a reading section for photoelectrically reading the radiation image information recorded on the stimulable phosphor sheet by applying simulating light to the stimulable phosphor sheet, and an erasing section for erasing remaining radiation image information from the stimulable phosphor sheet after the recorded image information has been read, the stimulable phosphor sheet being circulated or moved back and forth in the apparatus.
One known type of the radiation image information reading apparatus has an imaging bed that is horizontally movable. For example, as shown in FIG. 9 of the accompanying drawings, a conventional radiation image information reading apparatus 1 has a housing 2 and an imaging bed 3 floatingly supported on the top of the housing 2 for movement along two horizontal axes, i.e., X- and Y-axes. A patient 4, who is a subject to be imaged, lies on the imaging bed 3, with the back down, as shown, or one side down.
The operator 5 moves the imaging bed 3 along the X-axis or the Y-axis to bring a desired imaging area of the patient 4 into registration with the X-ray applying position of an X-ray radiating unit 6. Then, the operator 5 energizes the X-ray radiating unit 6 to capture radiation image information of the desired imaging area of the patient 4.
The radiation image information reading apparatus 1 has a lock mechanism for locking the imaging bed 3 at a desired vertical position. For moving the imaging bed 3, the operator 5 presses an unlock switch 7 on one side of the imaging bed 3 to cause the lock mechanism to release the imaging bed 3.
However, since the unlock switch 7 is positioned on one side of the imaging bed 3, the patient 4 may inadvertently press the unlock switch 7 when the patient 4 climbs on or off the imaging bed 3. When the patient 4 inadvertently presses the unlock switch 7, the imaging bed 3 can be moved undesirably because it is released from the lock mechanism. One solution is to position the unlock switch 7 remotely from the imaging bed 3. However, the operator 5 finds it awkward to press the remotely positioned unlock switch 7 in order to lock and unlock the imaging bed 3.
It is therefore an object of the present invention to provide a radiation image pickup apparatus which prevents an imaging bed from being inadvertently unlocked and allows the operator to operate the imaging bed efficiently.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.